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Summary Statement

The Carnegie-Spitzer-IMACS Redshift Survey

The Carnegie-Spitzer-IMACS (CSI) survey, currently underway at the Magellan-Baade
6.5m telescope in Chile, has been specifically designed to characterize normal galaxies and their environments
to z=1.5.

The survey selection is done using 3.6μm observations of
Spitzer Legacy fields, providing as close a selection by stellar mass as possible.

Using a low-dispersion prism in IMACS, the survey goal is
to study galaxies down to 21.0 AB mag in the 3.6μm
band over a 15 degs2. This area is defined by our goal of reducing
cosmic variance in the density of massive galaxies at z>1 to 10% in redshift bins of Δz=0.1. By doing so
we will be able to accurately trace the evolution of the galaxy mass function
to a time with the universe was a third of its current age. Over
this area, down to the magnitude limit of the survey, we expect to obtain low-dispersion
spectra for over 200,000 galaxies.

We combine the flux-calibrated spectroscopy with broadband optical-near IR colors, and use SED fitting to measure redshifts. In direct comparisons with previously published high resolution redshifts from the VVDS, our redshift accuracy is σz/(1+z)=1% for galaxies brighter than i'=23 mag and σz/(1+z)=2.5% for fainter galaxies. With this level of accuracy, CSI will be able to assemble a picture of how galaxies have evolved as functions of both mass and environment.